Combining ability analysis for high yield and low ODAP content in Lathyrus (Lathyrus sativus L.)

Introduction

Lathyrus sativus L., commonly known as grass pea or Kesari dal, is an important pulse crop belonging to the family Fabaceae. It is cultivated mainly for human consumption, livestock feed and fodder, particularly in regions where other crops perform poorly under adverse environmental conditions. The crop is well adapted to marginal and low-rainfall areas and possesses considerable tolerance to drought and other environmental stresses. In India, Lathyrus is cultivated mainly in states such as Uttar Pradesh, Bihar, West Bengal, Madhya Pradesh and Maharashtra, and contributes significantly to pulse production. Its ability to grow under rainfed conditions with relatively low cultivation inputs makes it an important crop for subsistence farming and food security. Grass pea is nutritionally valuable, with seeds containing substantial amounts of protein and carbohydrates, in addition to minerals and vitamins. The crop also contributes to soil fertility through biological nitrogen fixation, leaving a considerable amount of nitrogen for the succeeding crop. In several parts of India, Lathyrus is cultivated as a relay or utera crop in standing rice fields during the rabi season. Its adaptability to drought, low soil fertility and variable environmental conditions provides an opportunity for its expansion in marginal agricultural areas. Despite its agronomic and nutritional importance, the utilization and improvement of Lathyrus are constrained by the presence of the neurotoxin β-N-oxalyl-L-α,βdiaminopropionic acid (β-ODAP), which is associated with neurolathyrism when consumed in excessive quantities over prolonged periods.

Therefore, the development of high-yielding and low-ODAP Lathyrus varieties is an important objective of grass pea breeding programmes. Exploitation of genetic variability for yield, yield-contributing traits and ODAP content is essential for achieving these objectives. Combining ability analysis is an important tool in crop improvement for identifying superior parents and promising cross combinations. General combining ability (GCA) provides information on the average performance of parents in hybrid combinations and is mainly associated with additive genetic effects, whereas specific combining ability (SCA) indicates the performance of particular cross combinations and is largely related to non-additive genetic effects. Information on GCA and SCA helps breeders understand the genetic control of quantitative traits and facilitates the selection of suitable parents and cross combinations for developing improved varieties. The Line × Tester mating design provides an efficient approach for evaluating a large number of parental lines and their hybrids. It enables the estimation of GCA and SCA effects and assists in understanding the relative contribution of additive and non-additive gene action in the inheritance of economically important traits. Such information is valuable for formulating effective breeding strategies and identifying parents with desirable combining ability and superior cross combinations. Therefore, combining ability analysis of Lathyrus for yield, yield-contributing characters and ODAP content can provide useful information for the selection of elite parents and promising crosses. The identification of good combiners and superior cross combinations may contribute to the development of high-yielding and comparatively low-ODAP Lathyrus varieties, thereby supporting the improvement and wider utilization of this nutritionally important and stress-tolerant pulse crop.

Materials and Methods

The experimental material comprised of thirteen lines viz., NLK-6, NLK-42, NLK-37, NLK-56, NLK-102, NLK-49, NLK-74, NLK-73, NLK-38, EC-207071, NLM-12, NLM-17, NLM-23 and three testers viz., Ratan(check), Prateek(check) and Mahateora(check). During rabi 2024-25 thirteen lines and three testers were crossed following the Line × Tester mating design to obtain thirty-nine F₁ cross combinations. The resulting crosses, along with their parents and standard check varieties, were evaluated during the rabi season of 2025-26 in RBD design with three replications at the Research Farm of the Agricultural Botany Section, College of Agriculture, Nagpur. Observations were recorded on five randomly selected plants from each cross on days to first flowering, days to 50 % flowering, days to maturity, plant height, number of branches plant⁻¹, number of pods plant⁻¹, 100-seed weight(g), seed yield plant⁻¹(g) and ODAP content (%). The combining ability analysis was carried out as per standard method given by Kempthorne (1957) [4] and ANOVA as per Panse and Sukhatme(1954) [7] .

Result and Discussion

Analysis of variance for experimental design

The analysis of variance revealed highly significant differences among the genotypes for all the characters studied, indicating the presence of considerable genetic variability in the experimental material as presented in table 1. The variability observed among the parents and crosses provided sufficient scope for further assessment of combining ability and identification of superior parental lines and cross combinations for seed yield, yield-associated traits and ODAP content. In accordance to this results Lyngdoh et al. (2019) [5] , Nawale et al. (2024) [6] and Singh et al. (2025) [9] also observed significant genotypic variation for important agronomic traits in lathyrus.

Mean performance of parents and crosses

Most of the crosses exhibited intermediate mean performance of their respective parents for the characters studied, which may be attributed to the quantitative nature of these traits as observed from table 2. Out of the thirtynine crosses evaluated, seventeen crosses showed significant superiority over the standard check Ratan for days to maturity, sixteen for plant height, four each for number of branches plant⁻¹, number of pods plant⁻¹ and seed yield plant⁻¹ and eleven crosses for ODAP content in the desirable direction. The crosses NLM-23 × Ratan, NLM-12 × Ratan, NLM-12 × Prateek and NLK-73 × Prateek showed desirable performance for seed yield and important yield-contributing traits along with reduced ODAP content. However,according to Allard (1960) [1] per se performance of crosses gives only some indication of their usefulness in selecting potential crosses but their long term potential was not known, hence combining ability analysis was carried out for further evaluation. Similar to this result Gonmei et al. (2018) [3] , Sayyad et al. (2017) [8] , Nawale et al. (2024) [6] and Singh et al. (2025) also reported that the per se performance of the parents and crosses were not sufficient for identification of superior parents and crosses.

Analysis of variance for combining ability

The analysis of variance for combining ability revealed that the mean squares due to lines were highly significant for all the characters studied, indicating substantial differences among the lines in their general combining ability. The mean squares due to testers were significant for all the traits except plant height. The line × tester interaction was significant for all the characters except days to first flowering, indicating considerable variation among the cross combinations and the importance of specific combining ability as presented in table 3. The magnitude of mean squares due to lines was higher than that of testers for days to 50 per cent flowering, days to maturity, plant height, number of branches plant⁻¹, number of pods plant⁻¹ and seed yield. plant⁻¹, suggesting greater genetic diversity among the lines for these characters. The significant effects of lines, testers and line × tester interactions indicated the importance of both general and specific combining ability in the inheritance of the characters studied. Similar findings were reported by Sayyad et al. (2017) [8] and Nawale et al. (2024) [6] in lathyrus.

Predictability ratio and nature of gene action

The predictability ratio ranged from 0.68 for days to 50 per cent flowering to 0.99 for ODAP content. The predictability ratio was greater than 0.50 for all the characters, being 0.93 for days to first flowering, 0.68 for days to 50 per cent flowering, 0.69 for days to maturity, 0.69 for plant height, 0.76 for number of branches plant⁻¹, 0.73 for number of pods plant⁻¹, 0.75 for 100-seed weight, 0.69 for seed yield plant⁻¹ and 0.99 for ODAP content. The higher predictability ratios suggested the predominance of additive gene effects for the inheritance of the characters studied. The similar result was recorded by Sayyad et al. (2017) [8] , Nawale et al. (2024) [6] and Singh et al. (2025). This indicated that the predictability of superior performing crosses/progenies could be effectively done based on general combining ability effects of parents alone. Therefore, selection strategies based on crosses involving parents showing significant gca effects would be useful for the genetic improvement of these characters in Lathyrus. In contrary to this finding Sayyad et al. (2017) [8] and Nawale et al. (2024) [6] also observed the situation were the performance of the progeny can be judged or predicted on the basis of parents gca effects and sca effect of crosses for different traits.

General combining ability effects

The gca effects of thirteen lines were calculated for all the nine characters and for testers it was estimated for all characters except for plant height as presented in Table 4. When the gca effects were compared for the nine characters, lines NLM-12 and NLM-23 recorded significant positive gca effects for seed yield plant⁻¹, number of pods plant⁻¹, number of branches plant⁻¹ and plant height. Similarly, another line NLK-73 exhibited significant positive gca effects for seed yield plant⁻¹, number of pods plant⁻¹ and number of branches plant⁻¹. Hence, these three lines, NLM-12, NLM-23 and NLK-73, were identified as good general combiners and can be used in the crossing programme. Among the testers, Ratan recorded significant positive gca effects for 100-seed weight and number of branches, nonsignificant but positive gca effects for seed yield plant⁻¹ and number of pods plant⁻¹. So, Ratan can also be used as a good combiner parent in the crossing programme. These parents may therefore be utilized in future hybridization programmes for simultaneous improvement of seed yield and ODAP content.

Specific combining ability effects:

The sca effects of thirty-nine crosses for all characters except days to first flowering were calculated and presented in Table 5. The crosses with significant sca effect involved high × poor combining parents for seed yield plant⁻¹, number of pods plant⁻¹ and number of branches plant⁻¹ and for ODAP content, low × low and low × high combining parents. Specific combining ability effects of the crosses and the mean performance of the crosses were found to be in correspondence with one another. The mean performance of the identified crosses was intermediate between the two parents involved and at par with the superior check Ratan. Negative significant effects indicate the involvement of additive gene action for yield and yield components, which is a general situation in self-pollinated crops. Due to the presence of additive gene action in the crosses NLM-23 × Mahateora, NLM-23 × Prateek, NLM-12 × Mahateora and NLK-73 × Ratan, the genotypes of the inherent superiority can be produced from this population by blending and fixing maximum favourable genes. Improvement for seed yield can also be done by simple selection methods or any method which can effectively capitalize on additive gene action. These crosses also involved at least one parent having desirable GCA effects for seed yield and important yield components. Based on the mean performance of crosses, GCA effects of parents and SCA effects of cross combinations, NLM-23 × Mahateora, NLM-23 × Prateek, NLM-12 × Mahateora and NLK-73 × Ratan were identified as promising cross combinations. These crosses may be advanced to subsequent segregating generations and subjected to simple selection for the development of high-yielding lathyrus genotypes with reduced ODAP content. As the mean square due to tester was non-significant gca effect of lines were not estimated for plant height.

Conclusion

The present investigation demonstrated substantial genetic variability among the evaluated Lathyrus sativus genotypes, providing adequate scope for effective selection and genetic improvement. Combining ability analysis revealed significant contributions of lines, testers and line × tester interactions for most of the studied traits, indicating the involvement of both additive and non-additive genetic effects. The relatively high predictability ratios suggested a predominance of additive gene action, particularly for seed yield, yield-contributing traits and ODAP content, indicating the effectiveness of selection based on superior general combiners. NLM-12, NLM-23 and NLK-73 were identified as promising general combiners, while Ratan was a desirable tester for yield-associated traits. The crosses NLM-23 × Mahateora, NLM-23 × Prateek, NLM-12 × Mahateora and NLK-73 × Ratan showed desirable specific combining ability and promising performance. These parents and crosses can therefore be effectively utilized in future breeding programmes for developing high-yielding, agronomically superior and comparatively low-ODAP Lathyrus varieties.

Acknowledgement

AcknowledgmentsI gratefully acknowledge the invaluable contributions of everyone who supported and encouraged me to the make this research possible. My deepest thanks go to my research guide for their expert guidance and insightful feedback throughout the study. I also extend sincere appreciation to the Research Farm of the Agricultural Botany Section, College of Agriculture, Nagpur, for generously providing the facilities and resources essential to this work.

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